<div class="htmlview paragraph">Three mathematical models have been used to correlate over a thousand high-shear-rate viscosity data generated by CEC Committee CL-23 on multigrade reference oils, using shear rates up to 16000 s⁻¹ at 25°C and up to 1300 000 s⁻¹ at 150°C. The work has established that all three models provide a good fit for the data and that there is little difference between their precisions of fit.</div> <div class="htmlview paragraph">The constants found by fitting the three models to the high-shear-rate viscosities of fifteen multigrade reference oils of special interest to the CEC and the SAE/ASTM are recorded for future use.</div>